Mixed bit-types in single register

How can I test a register with multiple bit types (or field types) within the same register? So I have a register with bits 15:8 = read only and bits 7:0 are read/write. So I want to bit-bash this register, but bitbash does not test read only bits?
-Thanks

Since read-only fields are by definition not writable, you can’t bit bash them. If you want to check those bits you’re going to have to get more creative. You’ll need to do some operation on the device that changes those bits and read them out and check that you read the correct data.

As a side-note, testing write-only fields suffers from a similar problem. There you have to write the fields, perform an operation on the device that uses the fields and expect a certain behavior.